Szeth assassinated two Primes in a row, leading to the ascension of Gawx.[1]

To be elected Prime Aqasix, the viziers, scribes, and arbiters are each allowed to submit paperwork to convince the vizierate as a whole that they are worthy of the place. Only the scions are not able to apply, as they are traditionally visiting and blessing the settlements of the nation. The selection process is done in the presence of the new Prime, a symbolic ritual as the Azir believe they are never without a Prime so the election is to find out who the 'current' Prime is.

The Prime is considered a public asset, owned by the people. As such, there are lotteries for the chance to watch the Prime sleeping or eating.